Valve prostheses having an integral centering mechanism and methods of use thereof

ABSTRACT

A transcatheter valve prosthesis including a tubular stent, a prosthetic valve component disposed within and secured to the stent, and a centering mechanism coupled to and encircling an outer surface of the tubular stent. The centering mechanism includes a self-expanding centering ring having an expanded diameter in the expanded configuration that is greater than an expanded diameter of the tubular stent in the expanded configuration and a plurality of self-expanding spokes radially extending between the tubular stent and the centering ring. The centering mechanism may include a base ring and/or a skirt. Alternatively, the centering mechanism includes a plurality of self-expanding loops. When each loop is in a delivery configuration the loop has a straightened profile that proximally extends from a proximal end of the tubular stent. When each loop is in an expanded configuration the loop has a U-shaped profile radially spaced apart from the tubular stent.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional PatentApplication Ser. No. 62/134,754, filed Mar. 18, 2015, which is herebyincorporated by reference in its entirety for all purposes.

FIELD OF THE INVENTION

The invention relates to valve prostheses and more particularly to avalve prosthesis having an integral centering mechanism for positioningthe valve prosthesis in situ.

BACKGROUND OF THE INVENTION

A human heart includes four heart valves that determine the pathway ofblood flow through the heart: the mitral valve, the tricuspid valve, theaortic valve, and the pulmonary valve. The mitral and tricuspid valvesare atrioventricular valves, which are between the atria and theventricles, while the aortic and pulmonary valves are semilunar valves,which are in the arteries leaving the heart. Ideally, native leaflets ofa heart valve move apart from each other when the valve is in an openposition, and meet or “coapt” when the valve is in a closed position.Problems that may develop with valves include stenosis in which a valvedoes not open properly, and/or insufficiency or regurgitation in which avalve does not close properly. Stenosis and insufficiency may occurconcomitantly in the same valve. The effects of valvular dysfunctionvary, with regurgitation or backflow typically having relatively severephysiological consequences to the patient.

Recently, flexible prosthetic valves supported by stent or scaffoldstructures that can be delivered percutaneously using a catheter-baseddelivery system have been developed for heart and venous valvereplacement. These prosthetic valves may include either self-expandingor balloon-expandable stent structures with valve leaflets attached tothe interior of the stent structure. The prosthetic valve can be reducedin diameter, by compressing onto a balloon catheter or by beingcontained within a sheath component of a delivery system, and advancedthrough the venous or arterial vasculature. Once the prosthetic valve ispositioned at the treatment site, for instance within an incompetentnative valve, the stent structure may be expanded to hold the prostheticvalve firmly in place. One example of a stented prosthetic valve isdisclosed in U.S. Pat. No. 5,957,949 to Leonhardt et al. entitled“Percutaneous Placement Valve Stent”, which is incorporated by referenceherein in its entirety. Another example of a stented prosthetic valvefor a percutaneous pulmonary valve replacement procedure is described inU.S. Patent Application Publication No. 2003/0199971 A1 and U.S. Pat.No. 8,721,713, both filed by Tower et al., each of which is incorporatedby reference herein in its entirety.

Although transcatheter delivery methods have provided safer and lessinvasive methods for replacing a defective native heart valve,complications may arise including vessel trauma due to percutaneousdelivery within highly curved anatomy and/or due to a large deliveryprofile of the prosthesis, inaccurate placement of the valve prosthesis,conduction disturbances, coronary artery obstruction, and/or undesirableparavalvular leakage and/or regurgitation at the implantation site. Moreparticularly, for example, a prosthesis that is positioned too deeprelative to the native annulus or placed unevenly within the nativeannulus in terms of depth may cause conduction disturbances. In anotherexample, if a prosthesis is not circumferentially centered relative tothe native annulus, the deployed prosthesis may dislodge from theimplantation site and/or undesirable paravalvular leakage and/orregurgitation may occur. Thus, it is imperative that the prosthesis beaccurately located relative to the native annulus prior to fulldeployment of the prosthesis.

Embodiments hereof are directed to a transcatheter valve prosthesishaving an integral centering mechanism for positioning the valveprosthesis in situ to address one or more of the afore-mentionedcomplications.

BRIEF SUMMARY OF THE INVENTION

Embodiments hereof relate to a transcatheter valve prosthesis includinga tubular stent having a compressed configuration for delivery within avasculature and an expanded configuration for deployment within a nativeheart valve, a prosthetic valve component disposed within and secured tothe stent, and a centering mechanism coupled to and encircling an outersurface of the tubular stent. The centering mechanism has a compressedconfiguration for delivery within a vasculature and an expandedconfiguration for deployment within a native heart valve. The centeringmechanism includes a self-expanding centering ring having an expandeddiameter in the expanded configuration that is greater than an expandeddiameter of the tubular stent in the expanded configuration and aplurality of self-expanding spokes radially extending between thetubular stent and the centering ring.

In another embodiment hereof, a transcatheter valve prosthesis includesa tubular stent having a compressed configuration for delivery within avasculature and an expanded configuration for deployment within a nativeheart valve, a prosthetic valve component disposed within and secured tothe stent, and a plurality of self-expanding loops. A first end of eachloop is fixed to a proximal end of the tubular stent and a second end ofeach loop is slidingly coupled to the proximal end of the tubular stent,the first end of the loop being circumferentially spaced apart from thesecond end of the loop. When each loop is in the delivery configurationthe loop has a straightened profile that proximally extends from theproximal end of the tubular stent. When each loop is in the expandedconfiguration the loop has a U-shaped profile radially spaced apart froman outer surface of the tubular stent.

Embodiments hereof also relate to methods of delivering a valveprosthesis configured for implantation within a native valve annulus. Avalve delivery system having a valve prosthesis mounted thereon ispercutaneously introduced into the vasculature in a deliveryconfiguration. The valve prosthesis includes a tubular stent, aprosthetic valve component disposed within and secured to the stent, anda centering mechanism coupled to and encircling an outer surface of thetubular stent. The centering mechanism includes a self-expandingcentering ring and a plurality of self-expanding spokes radiallyextending between the tubular stent and the centering ring. The valvedelivery system is tracked through the vasculature until the valveprosthesis is positioned within the native valve annulus. At least aninflow end of the tubular stent is deployed into an expandedconfiguration. The tubular stent has an expanded diameter in theexpanded configuration. The centering mechanism of the valve prosthesisis deployed into an expanded configuration. The centering mechanism hasan expanded diameter that is greater than the expanded diameter of thetubular stent in the expanded configuration. The valve delivery systemis manipulated in order to catch the deployed centering mechanism ontothe native valve annulus, thereby longitudinally centering the valveprosthesis within the native valve annulus. An outflow end of thetubular stent is deployed into the expanded configuration.

Embodiments hereof also relate to methods of delivering a valveprosthesis configured for implantation within a native valve annulus. Avalve delivery system having a valve prosthesis mounted thereon ispercutaneously introduced into the vasculature in a deliveryconfiguration. The valve prosthesis includes a tubular stent, aprosthetic valve component disposed within and secured to the stent, anda centering mechanism coupled to and encircling an outer surface of thetubular stent. The centering mechanism includes a self-expandingcentering ring and a plurality of self-expanding spokes radiallyextending between the tubular stent and the centering ring. The valvedelivery system is tracked through the vasculature until the valveprosthesis is positioned within the native valve annulus. The centeringmechanism of the valve prosthesis is deployed into an expandedconfiguration. The centering mechanism has an expanded diameter that isgreater than the expanded diameter of the tubular stent in the expandedconfiguration and the centering mechanism catches onto the native valveannulus so as to be circumferentially and longitudinally centered withinthe native valve annulus. The tubular stent is deployed into an expandedconfiguration after deployment of the centering mechanism. The expandeddiameter of the deployed centering mechanism is greater than an expandeddiameter of the tubular stent in the expanded configuration and thedeployed centering mechanism pulls the tubular stent into acircumferentially and longitudinally centered position within the nativevalve annulus.

BRIEF DESCRIPTION OF DRAWINGS

The foregoing and other features and advantages of the invention will beapparent from the following description of embodiments hereof asillustrated in the accompanying drawings. The accompanying drawings,which are incorporated herein and form a part of the specification,further serve to explain the principles of the invention and to enable aperson skilled in the pertinent art to make and use the invention. Thedrawings are not to scale.

FIG. 1 is a side view illustration of an exemplary transcatheter valveprosthesis for use in embodiments hereof.

FIG. 1A is a top view illustration of the valve prosthesis of FIG. 1.

FIG. 1B is a side view illustration of an alternative configuration of avalve prosthesis for use in embodiments hereof.

FIG. 1C is a side view illustration of an alternative configuration of avalve prosthesis for use in embodiments hereof.

FIG. 2 is a side view illustration of a transcatheter valve prosthesishaving an integral centering mechanism according to an embodimenthereof, wherein the valve prosthesis and the centering mechanism are inexpanded or deployed configurations.

FIG. 2A is a cross-sectional view taken along line A-A of FIG. 2.

FIG. 3 is a cross-sectional view taken along line A-A of FIG. 2, whereinthe valve prosthesis and the centering mechanism are in compressed ordelivery configurations.

FIG. 4 is a cross-sectional view of a transcatheter valve prosthesishaving an integral centering mechanism according to another embodimenthereof, wherein a strand in woven between a stent and a centering ringto form a plurality of spokes, the valve prosthesis and the centeringmechanism being shown in their expanded or deployed configurations.

FIG. 5 is a cross-sectional view of a transcatheter valve prosthesishaving an integral centering mechanism according to another embodimenthereof, wherein the valve prosthesis includes a flexible skirt, thevalve prosthesis and the centering mechanism being shown in theirexpanded or deployed configurations.

FIG. 6 is an illustration of the transcatheter valve prosthesis of FIG.2 being delivered to a native aortic valve, wherein the valve prosthesisand the centering mechanism are compressed within a delivery system.

FIG. 7 is an illustration of the transcatheter valve prosthesis of FIG.2 being deployed within a native aortic valve, wherein an inflow end ofthe valve prosthesis and the centering mechanism are deployed.

FIG. 8 is an illustration of the transcatheter valve prosthesis of FIG.2 being deployed within a native aortic valve, wherein the centeringmechanism is positioned against the native aortic valve.

FIG. 9 is an illustration of the transcatheter valve prosthesis of FIG.2 being deployed within a native aortic valve, wherein an outflow end ofthe valve prosthesis is deployed.

FIG. 10 is a side view illustration of a transcatheter valve prosthesishaving an integral centering mechanism according to another embodimenthereof, wherein the valve prosthesis and the centering mechanism are inexpanded or deployed configurations.

FIG. 11 is a perspective view of the centering mechanism of FIG. 10removed from the other components of the valve prosthesis forillustrative purposes only, wherein the centering mechanism is in itsexpanded or deployed configuration.

FIG. 12 is a side view of a single spoke of the centering mechanism ofFIG. 11, wherein the spoke is in its expanded or deployed configuration.

FIG. 13 is an illustration of the transcatheter valve prosthesis of FIG.10 being delivered to a native aortic valve, wherein the valveprosthesis and the centering mechanism are compressed within a deliverysystem.

FIG. 13A is a side view of the transcatheter valve prosthesis of FIG.10, wherein the valve prosthesis and the centering mechanism are incompressed or delivery configurations.

FIG. 14 is an illustration of the transcatheter valve prosthesis of FIG.10 being deployed within a native aortic valve, wherein the centeringmechanism is deployed and the inflow end of the valve prosthesis ispartially deployed.

FIG. 15 is an illustration of the transcatheter valve prosthesis of FIG.10 deployed within a native aortic valve, wherein the centeringmechanism and the valve prosthesis are fully deployed.

FIG. 16 is an illustration of a transcatheter valve prosthesis accordingto another embodiment hereof deployed within a native aortic valve,wherein the transcatheter valve prosthesis includes a flexible skirt.

FIG. 17 is a side view illustration of a transcatheter valve prosthesishaving an integral centering mechanism according to another embodimenthereof, the centering mechanism including a plurality of loops, whereinthe valve prosthesis and the centering mechanism are in expanded ordeployed configurations.

FIG. 18 is a side view illustration of the transcatheter valveprosthesis of FIG. 17, wherein the valve prosthesis and the centeringmechanism are in compressed or delivery configurations.

FIG. 19 is a side view of a portion of the transcatheter valveprosthesis of FIG. 17 laid flat for illustrative purposes only, whereinthe stent and the loop thereof are in compressed or deliveryconfigurations.

FIG. 20 is a side view of a portion of the transcatheter valveprosthesis of FIG. 17 laid flat for illustrative purposes only, whereinthe stent and the loop thereof are in expanded or deployedconfigurations.

FIG. 21 is an illustration of the transcatheter valve prosthesis of FIG.17 being delivered to a native aortic valve, wherein the valveprosthesis and the centering mechanism are compressed within a deliverysystem.

FIG. 22 is an illustration of the transcatheter valve prosthesis of FIG.17 being deployed within a native aortic valve, wherein an outflow endof the valve prosthesis is partially deployed.

FIG. 23 is an illustration of the transcatheter valve prosthesis of FIG.17 being deployed within a native aortic valve, wherein the centeringmechanism is deployed and the outflow end of the valve prosthesis ispartially deployed.

FIG. 24 is an illustration of the transcatheter valve prosthesis of FIG.17 deployed within a native aortic valve, wherein the centeringmechanism and the valve prosthesis are fully deployed.

DETAILED DESCRIPTION OF THE INVENTION

Specific embodiments of the present invention are now described withreference to the figures, wherein like reference numbers indicateidentical or functionally similar elements. Unless otherwise indicated,the terms “distal” and “proximal” are used in the following descriptionwith respect to a position or direction relative to the treatingclinician. “Distal” and “distally” are positions distant from or in adirection away from the clinician, and “proximal” and “proximally” arepositions near or in a direction toward the clinician. In addition, theterm “self-expanding” is used in the following description and isintended to convey that the structures are shaped or formed from amaterial that can be provided with a mechanical memory to return thestructure from a compressed or constricted delivery configuration to anexpanded deployed configuration. Non-exhaustive exemplary self-expandingmaterials include stainless steel, a pseudo-elastic metal such as anickel titanium alloy or nitinol, various polymers, or a so-called superalloy, which may have a base metal of nickel, cobalt, chromium, or othermetal. Mechanical memory may be imparted to a wire or scaffold structureby thermal treatment to achieve a spring temper in stainless steel, forexample, or to set a shape memory in a susceptible metal alloy, such asnitinol. Various polymers that can be made to have shape memorycharacteristics may also be suitable for use in embodiments hereof toinclude polymers such as polynorborene, trans-polyisoprene,styrene-butadiene, and polyurethane. As well poly L-D lactic copolymer,oligo caprylactone copolymer and polycyclooctene can be used separatelyor in conjunction with other shape memory polymers. The term“substantially straight” and/or “straightened” is used in the followingdescription and is intended to convey that the structures are linearlyshaped or formed as a line within a tolerance of 5%.

The following detailed description is merely exemplary in nature and isnot intended to limit the invention or the application and uses of theinvention. Although the description of embodiments hereof are in thecontext of a transcatheter valve prosthesis within a native aorticvalve, the valve prostheses of the invention can also be used in otherareas of the body, such as within a native mitral valve, within a nativepulmonic valve, within a native tricuspid valve, within a venous valve,or within a failed previously-implanted prosthesis. Furthermore, thereis no intention to be bound by any expressed or implied theory presentedin the preceding technical field, background, brief summary or thefollowing detailed description.

FIG. 1 depicts an exemplary transcatheter valve prosthesis 100. Valveprosthesis 100 is illustrated herein in order to facilitate descriptionof the methods and components utilized to longitudinally and/orcircumferentially center the prosthesis according to embodiments hereof.It is understood that any number of alternate heart valve prostheses canbe used with the methods and devices described herein. Valve prosthesis100 is merely exemplary and is described in more detail in U.S. PatentApplication Pub. No. 2011/0172765 to Nguyen et al., which is hereinincorporated by reference in its entirety. Other non-limiting examplesof transcatheter valve prostheses are described in U.S. Pat. Appl. Pub.No. 2006/0265056 to Nguyen et al., U.S. Pat. Appl. Pub. No. 2007/0239266to Birdsall, U.S. Pat. Appl. Pub. No. 2007/0239269 to Dolan et al., andU.S. Pat. Appl. Pub. No. 2008/0071361 to Tuval et al., each of which isincorporated by reference herein in its entirety.

Valve prosthesis 100 includes an expandable stent or frame 102 thatsupports a prosthetic valve component within the interior of stent 102.In embodiments hereof, stent 102 is self-expanding to return to anexpanded deployed state from a compressed or constricted delivery stateand may be made from stainless steel, a pseudo-elastic metal such as anickel titanium alloy or Nitinol, or a so-called super alloy, which mayhave a base metal of nickel, cobalt, chromium, or other metal.Alternatively, valve prosthesis 100 may be balloon-expandable as wouldbe understood by one of ordinary skill in the art.

In the embodiment depicted in FIGS. 1 and 1A, stent 102 of valveprosthesis 100 has a deployed configuration including an enlarged orflared first end or section 116, a constriction or waist region 117, anda second end or section 118. Enlarged first section 116 has nominaldeployed diameter D₁, second section 118 has nominal deployed diameterD₂, and constriction region 117 has deployed substantially fixeddiameter D₃. Each section of stent 102 may be designed with a number ofdifferent configurations and sizes to meet the different requirements ofthe location in which it may be implanted. When configured as areplacement for an aortic valve, second section 118 functions as aninflow end of valve prosthesis 100 and extends into and anchors withinthe aortic annulus of a patient's left ventricle, while first section116 functions as an outflow end of valve prosthesis 100 and ispositioned in the patient's ascending aorta. When configured as areplacement for a mitral valve, enlarged or flared first section 116functions as an inflow end of valve prosthesis 100 and is positioned inthe patient's left atrium, while second section 118 functions as anoutflow end of valve prosthesis 100 and extends into and anchors withinthe mitral annulus of a patient's left ventricle. For example, U.S.Patent Application Publication Nos. 2012/0101572 to Kovalsky et al. and2012/0035722 to Tuval, each of which are herein incorporated byreference in their entirety, illustrate heart valve prosthesesconfigured for placement in a mitral valve. Each section of stent 102may have the same or different cross-section which may be for examplecircular, ellipsoidal, rectangular, hexagonal, rectangular, square, orother polygonal shape, although at present it is believed that circularor ellipsoidal may be preferable when the valve prosthesis is beingprovided for replacement of the aortic or mitral valve. As alternativesto the deployed configuration of FIGS. 1 and 1A, the stent/valve supportframe may have an hourglass configuration 102B shown in FIG. 1B, agenerally tubular configuration 102C as shown in FIG. 1C, or other stentconfiguration or shape known in the art for valve replacement. Stent 102also may include eyelets 108 that extend from first end 116 thereof foruse in loading the valve prosthesis 100 into a delivery catheter (notshown).

As previously mentioned, valve prosthesis 100 includes a prostheticvalve component within the interior of stent 102. The prosthetic valvecomponent is capable of blocking flow in one direction to regulate flowthere through via valve leaflets 104 that may form a bicuspid ortricuspid replacement valve. FIG. 1A is an end view of FIG. 1 andillustrates an exemplary tricuspid valve having three leaflets 104,although a bicuspid leaflet configuration may alternatively be used inembodiments hereof. More particularly, if valve prosthesis 100 isconfigured for placement within a native valve having three leafletssuch as the aortic, tricuspid, or pulmonary valves, valve prosthesis 100includes three valve leaflets 104. If valve prosthesis 100 is configuredfor placement within a native valve having two leaflets such as themitral valve, valve prosthesis 100 includes two valve leaflets 104.Valve leaflets 104 are sutured or otherwise securely and sealinglyattached to the interior surface of stent 102 and/or graft material 106which encloses or lines a portion of stent 102 as would be known to oneof ordinary skill in the art of prosthetic tissue valve construction.Referring to FIG. 1, leaflets 104 are attached along their bases 110 tograft material 106, for example, using sutures or a suitablebiocompatible adhesive. Adjoining pairs of leaflets are attached to oneanother at their lateral ends to form commissures 120, with free edges122 of the leaflets forming coaptation edges that meet in area ofcoaptation 114.

Leaflets 104 may be made of pericardial material; however, the leafletsmay instead be made of another material. Natural tissue for replacementvalve leaflets may be obtained from, for example, heart valves, aorticroots, aortic walls, aortic leaflets, pericardial tissue, such aspericardial patches, bypass grafts, blood vessels, intestinal submucosaltissue, umbilical tissue and the like from humans or animals. Syntheticmaterials suitable for use as leaflets 104 include DACRON® polyestercommercially available from Invista North America S.A.R.L. ofWilmington, Del., other cloth materials, nylon blends, polymericmaterials, and vacuum deposition nitinol fabricated materials. Onepolymeric material from which the leaflets can be made is an ultra-highmolecular weight polyethylene material commercially available under thetrade designation DYNEEMA from Royal DSM of the Netherlands. Withcertain leaflet materials, it may be desirable to coat one or both sidesof the leaflet with a material that will prevent or minimize overgrowth.It is further desirable that the leaflet material is durable and notsubject to stretching, deforming, or fatigue.

Graft material 106 may also be a natural or biological material such aspericardium or another membranous tissue such as intestinal submucosa.Alternatively, graft material 106 may be a low-porosity woven fabric,such as polyester, Dacron fabric, or PTFE, which creates a one-way fluidpassage when attached to the stent. In one embodiment, graft material106 may be a knit or woven polyester, such as a polyester or PTFE knit,which can be utilized when it is desired to provide a medium for tissueingrowth and the ability for the fabric to stretch to conform to acurved surface. Polyester velour fabrics may alternatively be used, suchas when it is desired to provide a medium for tissue ingrowth on oneside and a smooth surface on the other side. These and other appropriatecardiovascular fabrics are commercially available from Bard PeripheralVascular. Inc. of Tempe, Ariz., for example. In one embodiment shown inFIG. 1, graft material 106 extends from leaflets bases 110 to second end118 of valve prosthesis.

As previously described herein, proper positioning of a transcathetervalve prosthesis is required in order to successfully implant the valveprosthesis within a native valve annulus. If the prosthesis isincorrectly positioned relative to the native valve annulus, thedeployed device can leak and dislodge from the implantation site.Embodiments hereof are directed to a transcatheter valve prosthesishaving an integral centering mechanism for positioning the valveprosthesis in situ such that the valve prosthesis is longitudinallyand/or circumferentially centered in a native valve annulus at thetarget implantation site, such as for example a native aortic valve. Asused herein, “circumferentially centered” and/or “circumferentiallycenter” include a prosthesis that is placed or situated in the center ofa body lumen such that a centerpoint of the prosthesis is equidistant tothe vessel wall of the body lumen within a tolerance of 10% of the meanlumen diameter of the body lumen. As used herein, “lumen diameter” for acircular body lumen is the diameter of the circular lumen, “lumendiameter” for an eccentric or non-circular body lumen is the diameter ofa circular lumen with an equivalent perimeter length, and “lumendiameter” for an oval body lumen is the average of the major and minordiameters of the oval lumen. As used herein, “longitudinally centered”and/or “longitudinally center” include a valve prosthesis having adistal end that is positioned or implanted between 0 mm and 6 mm distalto the native valve annulus within a tolerance of +/−2 mm. Thelongitudinal centering devices described herein prevent the valveprosthesis from being implanted too deep or too shallow into the leftventricle relative to the native annulus. The circumferential and/orlongitudinal centering devices described herein serve to eliminate orminimize canting of an implanted valve prosthesis, or stated anotherway, serve to position a valve prosthesis in situ such that afterimplantation thereof the valve plane of the valve prosthesis issubstantially (i.e., within the tolerances stated above) parallel to thevalve plane of the native valve.

More particularly, FIG. 2 is a side view of a transcatheter valveprosthesis 200 according to an embodiment hereof. Similar totranscatheter valve prosthesis 100, transcatheter valve prosthesis 200includes a tubular stent 202 having a compressed configuration fordelivery within a vasculature and an expanded configuration fordeployment within a native heart valve and a prosthetic valve componentincluding leaflets 204 disposed within and secured to stent 202. Stent202 includes a first end 216 and a second end 218, and graft material206 encloses or lines a portion of stent 202. Valve prosthesis 200 alsoincludes a centering mechanism 220 coupled to and encircling an outersurface of tubular stent 202. Centering mechanism 220 includes aself-expanding centering ring 222 and a plurality of spokes 224 radiallyextending between tubular stent 202 and centering ring 222. Centeringmechanism 220 has a compressed configuration for delivery within avasculature, as will be described in more detail herein with respect toFIG. 3, and an expanded configuration for deployment within a nativeheart valve. Centering mechanism 220 and stent 202 are shown in theirexpanded configurations in FIG. 2. In their expanded configurations,centering ring 222 has an expanded diameter that is greater than anexpanded diameter of tubular stent 202 such that centering ring 222 isradially spaced apart from the outer surface of tubular stent 202.

When deployed, centering ring 222 is configured to abut against anabutment surface defined by a native valve annulus to longitudinallycenter valve prosthesis 200 within the native valve annulus. Moreparticularly, as will be described in more detail with reference to FIG.7, centering ring 222 is configured to be initially positioned in situslightly above the abutment surface defined by the native valve annulus.Valve prosthesis 200, including centering mechanism 220, is thentranslated or moved such that centering ring 222 contacts or abutsagainst the abutment surface of the native valve annulus. As such,centering ring 222 is utilized as a depth marker or reference point tolongitudinally center valve prosthesis 200 by preventing the valveprosthesis from being positioned too deep or too shallow within the leftventricle.

FIG. 2A is a cross-sectional view taken along line A-A of FIG. 2, withleaflets 204 removed for sake of illustration only. In FIG. 2A,centering mechanism 220 and stent 202 are shown in their expandedconfigurations in which centering ring 222 has an expanded diameter thatis greater than an expanded diameter of tubular stent 202 such thatcentering ring 222 is radially spaced apart from the outer surface oftubular stent 202 with spokes 224 radially extending between tubularstent 202 and centering ring 222. When expanded, spokes 224 aresubstantially straight or linear and centering mechanism 220 has a flatprofile that extends transverse with respect to the longitudinal axis oftranscatheter valve prosthesis 200. Depending upon the size of thepatient, the expanded diameter of centering ring 222 may vary between 20mm and 40 mm. Centering ring 222 is required to be sized greater thanthe opening defined by the native valve annulus so that the centeringring contacts or abuts against an abutment surface defined by the nativevalve annulus during use thereof. Since centering mechanism 220 iscoupled to the outer surface of valve prosthesis 200, longitudinalplacement and/or the size and shape thereof may be adjusted or adaptedaccording to each application and to a patient's unique needs. Forexample, depending on the anatomy of the particular patient, centeringmechanism 220 may be placed closer to second end 218 than shown and/orcentering ring 222 may have an expanded diameter that is greater or lessthan the expanded diameter shown in FIG. 2.

FIG. 3A is a cross-sectional view taken along line A-A of FIG. 2, withleaflets 204 removed for sake of illustration only, with centeringmechanism 220 and stent 202 shown in their compressed or deliveryconfigurations. In the compressed or delivery configuration, spokes 224bend or radially collapse such that the diameter of ring 222 isapproximately equal to or slightly larger than the compressed ordelivery diameter of stent 202. Centering ring 222 and spokes 224 areformed from a self-expanding material and shape-set in the deployed orexpanded configuration such that centering mechanism 220 returns to theexpanded or deployed configuration of FIGS. 2 and 2A after beingradially compressed or constricted for delivery.

Although centering mechanism 220 is shown with eight spokes 224circumferentially spaced apart with respect to tubular stent 202,centering mechanism 220 may include a greater number of spokes or afewer number of spokes, depending upon application. Each spoke 224 is anindividual or separate strand of material having opposing ends thereofattached or fixed to ring 222 and tubular stent 202. The opposing endsof each spoke 224 may be attached to ring 222 and tubular stent 202 byany suitable means known to those skilled in the art, for example andnot by way of limitation, welding, adhesive, suture, or mechanicalcoupling. In an embodiment hereof, centering mechanism 220 is alsoconfigured to circumferentially center valve prosthesis 200 within thenative valve annulus. More particularly, an outer surface of centeringmechanism 220 is sized and configured to contact and abut against aninner surface of the native valve annulus and spokes 224 are configuredto have sufficient rigidity to circumferentially center valve prosthesis220. In an embodiment hereof, spokes 224 may have a thickness between0.05 mm and 0.5 mm in order to be achieve the desired circumferentiallycentering objective while still being flexible enough to collapse fordelivery.

In another embodiment hereof, the plurality of spokes may be formed witha single strand of material that is woven between the tubular stent andthe centering ring. More particularly, as shown on FIG. 4, spokes 424are formed via a single strand 425 of material. Strand 425 is wovenbetween stent 202 and centering ring 222 in order to form a plurality ofspokes 424 radially extending between tubular stent 202 and centeringring 222. Strand 425 may be woven between the openings or cells formedwithin stent 202 and looped around the centering ring 222. After thedesired number of circumferentially spaced apart spokes 424 are formed,the ends of strand 425 may be coupled together such that strand 425 is aring formed from a self-expanding material and shape-set in the deployedor expanded configuration such that centering mechanism 420 returns tothe expanded or deployed configuration of FIG. 4 after being radiallycompressed or constricted for delivery.

In another embodiment hereof, a flexible skirt material may be attachedto an outer surface of the centering mechanism. More particularly, asshown in the embodiment of FIG. 5, a centering mechanism 520 is similarto centering mechanism 420 and includes self-expanding centering ring222 and a plurality of spokes 224 radially extending between tubularstent 202 and centering ring 222. In addition, a flexible skirt 526 isdisposed over an outer surface of centering ring 222 and spokes 224. Theskirt is formed from a low-porosity woven fabric or pericardial tissueand serves as a sealing element in situ to block or prevent retrogradeblood flow around the outside of tubular stent 202, thereby minimizingand/or eliminating any paravalvular leakage at the implantation site.

Delivery and deployment of transcatheter valve prosthesis 200 will nowbe described with reference to FIGS. 6-9. A valve delivery system 630having transcatheter valve prosthesis 200 mounted thereon ispercutaneously introduced into the vasculature, with transcatheter valveprosthesis 200 in a delivery configuration. Valve delivery system 630includes a tubular outer shaft 632 defining a lumen there-through and atubular inner shaft 636 (shown on FIG. 7) defining a lumenthere-through. A distal tip 634 is coupled to a distal end of innershaft 636. Inner shaft 636 is concentrically disposed within the lumenof outer shaft 632, and the lumen of inner shaft 636 may be sized toslidingly receive a guidewire (not shown) such that valve deliverysystem 630 may be tracked over the guidewire during delivery oftranscatheter valve prosthesis 200. In the delivery configuration ofFIG. 1, a distal portion of outer shaft 632 is disposed overtranscatheter valve prosthesis 200 to compressively retain thetranscatheter valve prosthesis in crimped engagement with inner shaft636. Valve delivery system 630 may be one of, but is not limited to, thedelivery systems described in U.S. Patent Publication No. 2011/0245917to Savage et al., U.S. Patent Publication No. 2011/0251675 to Dwork,U.S. Patent Publication No. 2011/0251681 to Shipley et al., U.S. PatentPublication No. 2011/0251682 to Murray, Ill. et al., and U.S. PatentPublication No. 2011/0264202 to Murray, Ill. et al., each of which isherein incorporated by reference in its entirety.

Valve delivery system 630 is tracked through the vasculature untiltranscatheter valve prosthesis 200 is positioned within the native valveannulus as shown in FIG. 6. During delivery, transcatheter valveprosthesis 200 remains compressed within valve delivery system 630.Delivery of transcatheter valve prosthesis 200 may be accomplished inaccordance with techniques known in the field of interventionalcardiology and/or interventional radiology. In an embodiment hereof,transcatheter valve prosthesis 200 is configured for implantation in atarget diseased native aortic valve AV that extends between a patient'sleft ventricle LV and a patient's aorta A. The coronary arteries C_(A)are also shown on the sectional view of FIG. 6. Transcatheter valveprosthesis 200 is configured for implantation via a percutaneoustransfemoral approach and valve delivery system 630 is transluminallyadvanced in a retrograde approach through the vasculature to thetreatment site. More particularly, valve delivery system 630 is trackedthrough the femoral artery, up the aorta and around the aortic arch inorder to access the native aortic valve AV. Transcatheter valveprosthesis 200 may also be positioned within the desired area of theheart via different delivery methods known in the art for accessingheart valves.

After transcatheter valve prosthesis 200 is positioned within the nativevalve annulus as desired, at least second or inflow end 218 of tubularstent 202 and centering mechanism 220 are deployed into an expandedconfiguration as shown in FIG. 7. More particularly, outer shaft 632 isretracted to release second or inflow end 218 of tubular stent 202 andcentering mechanism 220, which are permitted to resume their shape-set,deployed configurations via self-expansion. At this stage of deployment,centering ring 222 is positioned in situ slightly above an abutmentsurface 637 defined by the native valve annulus.

Valve delivery system 630 is then manipulated in order to catch orcontact deployed centering mechanism 220 onto abutment surface 637 ofthe native valve annulus. More particularly, valve delivery system 630is distally advanced in order to translate or move valve prosthesis 200and centering mechanism 220 until centering ring 222 contacts or abutsagainst abutment surface 637 of the native valve annulus as shown inFIG. 8. As such, centering ring 222 is utilized as a depth marker orreference point to longitudinally center valve prosthesis 200 bypreventing the valve prosthesis from being positioned too deep or tooshallow within the left ventricle LV.

Once centering ring 222 is positioned as desired, the first or outflowend 216 of tubular stent 202 is deployed into the expanded configurationas shown in FIG. 9. More particularly, outer shaft 632 is retracted torelease first or outflow end 216 of tubular stent 202, which ispermitted to resume its shape-set, deployed configuration viaself-expansion. If the position of transcatheter valve prosthesis 200needs to be adjusted after deployment, transcatheter valve prosthesis200 including integral centering mechanism 220 may be recaptured bydistally advancing outer shaft 632 there-over to return transcathetervalve prosthesis 200 and integral centering mechanism 220 to theirdelivery configurations. When transcatheter valve prosthesis 200 ispositioned as desired, valve delivery catheter 630 is then removed andtranscatheter valve prosthesis 200 remains deployed within the nativetarget heart valve.

In the embodiments of FIGS. 2-9, centering mechanism 220 has a flatprofile that extends transverse with respect to the longitudinal axis oftranscatheter valve prosthesis 200. A centering mechanism 1020 having adifferent configuration or profile is shown in FIGS. 10 and 11. FIG. 10is a side view of centering mechanism 1020 coupled to and encircling anouter surface of tubular stent 202, while FIG. 11 is a perspective viewof centering mechanism 1020 removed from the tubular stent forillustrative purposes only. Centering mechanism 1020 and stent 202 areshown in their expanded configurations in FIGS. 10 and 11. Similar tocentering mechanism 220, centering mechanism 1020 includes aself-expanding centering ring 1022 and a plurality of spokes 1024radially extending between tubular stent 202 and centering ring 1022. Intheir expanded configurations, centering ring 1022 has an expandeddiameter that is greater than an expanded diameter of tubular stent 202such that centering ring 1022 is radially spaced apart from the outersurface of tubular stent 202. However, in this embodiment, centeringmechanism 1020 also includes a base ring 1038 attached to tubular stent202 which has expanded diameter equal to the expanded diameter of thetubular stent. Base ring 1038 and centering ring 1022 are longitudinallyspaced apart by a distance D, with base ring 1038 being positionedproximal to centering ring 1022. In an embodiment, distance D may varybetween 0.25 inches and 2.00 inches. Base ring 1038 may be attached tostent 202 by any suitable means known to those skilled in the art, forexample and not by way of limitation, welding, adhesive, suture, ormechanical coupling.

Centering mechanism 1020 may include a greater number of spokes or afewer number of spokes, depending upon application. Each spoke 1024 isan individual or separate strand of material having opposing ends 1040,1042 attached or fixed to base ring 1038 and centering ring 1022,respectively. A side view of a single spoke 1024 is shown in FIG. 12,the spoke being removed from the centering mechanism for illustrationpurposes only. Spokes 1024, as well as base ring 1038 and centering ring1022, are formed from a self-expanding material and shape-set in thedeployed or expanded configuration such that centering mechanism 1020returns to the expanded or deployed configuration of FIGS. 10 and 11after being radially compressed or constricted for delivery. In itsdeployed or expanded configuration, each spoke 1024 may be considered toinclude a first longitudinal portion 1044 and a second longitudinalportion 1046. First and second longitudinal portions 1044, 1046 arecontinuous or integral with each other but are described separatelyherein due to their differing shapes. In an embodiment, first and secondlongitudinal portions 1044, 1046 each extend one-half of the totallength of spoke 1024. First longitudinal portion 1044 is substantiallystraight or linear, while second longitudinal portion 1046 curves orflares radially outward. The shapes of first and second longitudinalportions 1044, 1046 match or correspond with the shape of a nativeaortic valve.

When deployed, as will be described in more detail with respect to FIGS.14-15, centering ring 1022 is configured to abut against a native valveannulus to both circumferentially and longitudinally center valveprosthesis 1000 within the native valve annulus. As described withrespect to centering ring 222, centering ring 1022 is configured to abutagainst an abutment surface of a native valve annulus such thatcentering ring 222 serves as a depth marker or reference point tolongitudinally center valve prosthesis 1000 by preventing the valveprosthesis from being positioned too deep or too shallow within the leftventricle. In addition, an outer surface of centering mechanism 1020 issized and configured to contact and abut against an inner surface of thenative valve annulus and spokes 1024 are configured to have sufficientrigidity to circumferentially center valve prosthesis 1000. Dependingupon the size of the patient, the expanded diameter of centering ring1022 may vary between 0.50 inches and 3.00 inches. In an embodimenthereof, spokes 1024 may have a thickness between 0.01 inches and 0.2inches in order to be achieve the desired circumferentially centeringobjective while still being flexible enough to collapse for delivery.

Delivery and deployment of transcatheter valve prosthesis 1000 will nowbe described with reference to FIGS. 13-15. Valve delivery system 630having transcatheter valve prosthesis 1000 mounted thereon ispercutaneously introduced into the vasculature, with transcatheter valveprosthesis 1000 in a delivery configuration. As described with respectto FIG. 6, valve delivery system 630 includes tubular outer shaft 632tubular inner shaft 636, and a distal tip 634 which is coupled to adistal end of the inner shaft. In the delivery configuration of FIG. 13,a distal portion of outer shaft 632 is disposed over transcatheter valveprosthesis 1000 to compressively retain the transcatheter valveprosthesis in crimped engagement with inner shaft 636. FIG. 13A is aside view of centering mechanism 1020 and stent 1002 shown in theircompressed or delivery configurations, although the delivery system isnot shown for sake of clarity. In the compressed or deliveryconfiguration, base ring 1038 and centering ring 1022 each have acompressed diameter that is substantially equal to or only slightlygreater than a compressed or delivery diameter of tubular stent 202.Spokes 1024 are substantially straight or linear, and lie flat or flushwith an outer surface of compressed tubular stent 202. Since centeringring 1022 is not coupled or attached to the outer surface of tubularstent 202, centering ring 1022 slides or moves along the outer surfaceof tubular stent 202 towards second or inflow end 218 of tubular stent202 in order to allow spokes 1024 to straighten into their deliveryconfigurations.

Valve delivery system 630 is tracked through the vasculature untiltranscatheter valve prosthesis 1000 is positioned within the nativevalve annulus as shown in FIG. 13. During delivery, transcatheter valveprosthesis 1000 remains compressed within valve delivery system 630.Delivery of transcatheter valve prosthesis 1000 may be accomplished inaccordance with techniques known in the field of interventionalcardiology and/or interventional radiology. In an embodiment hereof,transcatheter valve prosthesis 1000 is configured for implantation in atarget diseased native aortic valve AV that extends between a patient'sleft ventricle LV and a patient's aorta A. The coronary arteries C_(A)are also shown on the sectional view of FIG. 13. Transcatheter valveprosthesis 1000 is configured for implantation via a percutaneoustransfemoral approach and valve delivery system 630 is transluminallyadvanced in a retrograde approach through the vasculature to thetreatment site. More particularly, valve delivery system 630 is trackedthrough the femoral artery, up the aorta and around the aortic arch inorder to access the native aortic valve AV. Transcatheter valveprosthesis 1000 may also be positioned within the desired area of theheart via different delivery methods known in the art for accessingheart valves.

After transcatheter valve prosthesis 1000 is positioned within thenative valve annulus as desired, at least second or inflow end 218 oftubular stent 202 and centering mechanism 1020 are deployed into anexpanded configuration as shown in FIG. 14. More particularly, outershaft 632 is retracted to release second or inflow end 218 of tubularstent 202 and centering mechanism 1020, which are permitted to resumetheir shape-set, deployed configurations via self-expansion. However,due to the geometry/profile and radial force of centering mechanism1020, centering mechanism 1020 is configured to self-expand at a fasterrate than tubular stent 202 as shown in FIG. 14. As such, centeringmechanism 1020 reaches its deployed or expanded configuration whiletubular stent 202 is still in a compressed configuration or is onlypartially deployed in that second or inflow end 218 of tubular stent 202has not yet reached its fully deployed or expanded diameter.

In FIG. 14, centering ring 1022 is shown deployed onto abutment surface1437 of the native valve annulus. As such, centering ring 1022 isutilized as a depth marker or reference point to longitudinally centervalve prosthesis 1000 by preventing the valve prosthesis from beingpositioned too deep or too shallow within the left ventricle LV.However, if centering ring 1022 deploys above abutment surface 1437 ofthe native valve annulus, valve delivery system 630 may be manipulatedin order to catch or contact deployed centering mechanism 1020 ontoabutment surface 1437 of the native valve annulus. More particularly,valve delivery system 630 may be distally advanced in order to translateor move valve prosthesis 1000 and centering mechanism 1020 untilcentering ring 1022 contacts or abuts against abutment surface 1437 ofthe native valve annulus as shown in FIG. 14.

When fully deployed, centering ring 1022 contacts or abuts against aninner surface 1448 of the native valve annulus as shown in FIG. 14 andthereby circumferentially self-centers itself within the native valveannulus. As such, since centering ring 1022 is circumferentiallycentered, centering mechanism 1020 pulls or locates tubular stent 202into a circumferentially centered positioned as the tubular stent 202expands to its fully deployed configuration as shown in FIG. 15. If notpreviously released from the delivery system, first or outflow end 216of tubular stent 202 is then deployed into the expanded configurationvia retraction of outer shaft 632 as shown in FIG. 15. If the positionof transcatheter valve prosthesis 1000 needs to be adjusted afterdeployment, transcatheter valve prosthesis 1000 including integralcentering mechanism 1020 may be recaptured by distally advancing outershaft 632 there-over to return transcatheter valve prosthesis 1000 andintegral centering mechanism 1020 to their delivery configurations. Whentranscatheter valve prosthesis 1000 is positioned as desired, valvedelivery catheter 630 is then removed and transcatheter valve prosthesis1000 remains deployed within the native target heart valve. Deploymentof transcatheter valve prosthesis 1000 may thus be considered to occurvia two consecutive stages with a first stage of deployment includingdeployment of centering mechanism 1020 and a second stage of deploymentincluding deployment of tubular stent 202 having a prosthetic valvecomponent therein.

In an embodiment hereof, a flexible skirt material may be attached to anouter surface of centering mechanism 1020. More particularly, as shownin the embodiment of FIG. 16, a centering mechanism 1620 is similar tocentering mechanism 1020 and includes self-expanding centering ring1622, a base ring 1638, and a plurality of spokes 1624 radiallyextending between tubular stent 202 and centering ring 1622. Inaddition, a flexible skirt 1626 is disposed over an outer surface ofcentering ring 1622 and spokes 1624. The skirt is formed from alow-porosity woven fabric or pericardial tissue and serves as a sealingelement in situ to block or prevent retrograde blood flow around theoutside of tubular stent 202, thereby minimizing and/or eliminating anyparavalvular leakage at the implantation site. Since skirt 1626 isattached to self-expanding centering ring 1622, centering ring 1622operates to radially extend or deploy an edge of skirt 1626 outwardlyaway from stent 202 to form an open-ended annular pocket or compartment1649 between an inner surface of the skirt and the outer surface of thetubular stent. Open-ended pocket 1649 catches blood flow around theouter perimeter of the prosthesis and blocks any retrograde flow withinthe native valve, thereby preventing undesired regurgitation andpreventing blood stagnation in and around the native valve sinuses.Open-ended pocket 1649 functions as a continuous circumferential sealaround transcatheter valve prosthesis 1600 to block or prevent bloodflow around the outer perimeter of the prosthesis, thereby minimizingand/or eliminating any paravalvular leakage at the implantation site.

A centering mechanism 1720 including a plurality of self-expanding loopsis shown in FIG. 17. Centering mechanism 1720 and stent 202 are shown intheir expanded configurations in FIG. 17 and in their deliveryconfigurations in FIG. 18, although only the outline or profile of stent202 is shown and the wireframe pattern is omitted for sake of clarity.In this embodiment, centering mechanism 1720 includes a plurality ofself-expanding loops 1750 that may be deployed within the cusps of theaortic annulus to longitudinally center transcatheter valve prosthesis1700 within the native valve annulus. The three self-expanding loops1750 are circumferentially spaced apart at approximately 120 degreeintervals around first or outflow end 216 of tubular stent 202. Althoughcentering mechanism 1720 is shown with three self-expanding loops 1750,centering mechanism 1720 may include a greater number of self-expandingloops or a fewer number of self-expanding loops, depending uponapplication.

Loops 1750 are generally shown in the figures as being a wire or tubularstructure formed into a U-shaped or generally U-shaped configurationsuch that each loop has two opposing side segments 1772, 1774 with abottom curved segment 1770. As will be understood by those of ordinaryskill in the art, “side” and “bottom” are relative terms and utilizedherein for illustration purposes only. The straight side segments may beparallel to each other, or may be slanted or angled away from each otheras shown in FIG. 17 in which two straight slanted side segments 1772,1774 flare apart as they extend from bottom curved segment 1770. Asutilized herein, “generally” U-shaped includes wire or tubularstructures formed into a horseshoe shape, a semi-circle, an oblong shapein which two parallel straight side segments have a generally straightbottom segment therebetween, and a V shape in which two straight slantedside segments are connected together by a curved apex. The loops may beconsiderably longer, shorter, wider, or narrower than shown. In anycase, the loops are preferably configured to be a shape and size thatcan provide a positioning function and an anchoring function for valveprosthesis 1700 when the prosthesis is deployed at a native valve targetsite. For example, if valve prosthesis 1700 is positioned within thenative aortic valve annulus, the loops extend from first or outflow end216 of stent 202 and provide interference with the native valve leafletsand/or the walls of the native valve annulus, thereby inhibiting motionof valve prosthesis 1700 to achieve anchoring of the valve prosthesis.In addition, loops 1750 are positioned in the coronary cusps to provideanatomical and accurate positioning of transcatheter valve prosthesis1700 prior to deployment of the transcatheter valve prosthesis. Inparticular, since self-expanding loops 1750 are positioned in thecoronary cusps, centering mechanism 1720 provides both depth control aswell as rotational alignment in order to properly position transcathetervalve prosthesis 1700.

Deployment of loops 1750 will now be discussed in more detail withreference to FIG. 19 and FIG. 20. FIGS. 19 and 20 illustrate a portionof stent 202 laid flat for illustrative purposes, with a single loop1750 coupled thereto. With reference to FIG. 18 and FIG. 19, in thecompressed or delivery configuration, loop 1750 is approximatelyparallel with a longitudinal axis L_(a) of stent 202 and proximallyextends from first or outflow end 216 of stent 202. A first end 1752 isattached or fixed to first or outflow end 216 of stent 202 and a secondend 1754 is slidingly coupled to first or outflow end 216 of stent 202at a circumferentially spaced-apart location from first end 1752. Moreparticularly, loop 1750 is threaded through an eyelet 1758 also attachedor fixed to first or outflow end 216 of stent 202 such that second end1754 is circumferentially spaced-apart from first or outflow end 216 ofstent 202. A ball 1756 is attached to second end 1754 of loop 1750. Ball1756 has a diameter greater than the opening defined by eyelet 1754 sothat ball 1756 is sized to not pass through eyelet 1754. The addition ofself-expanding loops 1750 to the profile of the delivery system isminimized because self-expanding loops 1750 are straightened and flushwith the delivery system during delivery and also because self-expandingloops 1750 are positioned proximal to stent 202 rather than stacked orin parallel with the stent.

Each loop 1750 is formed from a self-expanding material such as Nitinoland shape-set in the deployed or expanded configuration shown in FIG.17. Stated another way, the low energy configuration of each loop 1750is the deployed or expanded configuration shown in FIG. 17. Balls 1756may be utilized to straighten loops 1750 for delivery by pulling secondends 1754 into a delivery system. The delivery system retains loops inthe delivery configuration until it is desired to deploy loops 1750.When loops 1750 are released from the delivery system, each loop 1750 ispermitted to self-expand and resume its deployed or expandedconfiguration. With reference to FIG. 20, when loops 1750 self-expand,each loop 1750 slides through a respective eyelet 1756 and second ends1754 of loops 1750 move towards first or outflow end 216 of stent 202until balls 1756 contact or abut against eyelets 1758. As previouslydescribed, eyelets 1758 are sized to prevent second ends 1754 of loops1750 from passing there-through.

Delivery and deployment of transcatheter valve prosthesis 1700 will nowbe described with reference to FIGS. 21-24. A valve delivery system 2130having transcatheter valve prosthesis 1700 mounted thereon ispercutaneously introduced into the vasculature, with transcatheter valveprosthesis 1700 in a delivery configuration. Valve delivery system 2130utilizes multiple tubes or capsules to deploy centering mechanism 1720and transcatheter valve prosthesis 1700. A first or proximal capsule ortube 2131 is proximally retracted in the ascending aorta duringdeployment to deploy centering mechanism 1720 and then a second ordistal capsule or tube 2133 is distally advanced to deploy stent 202.For example, valve delivery system 2130 may be, but is not limited to,the delivery system which is utilized to deploy the ENGAGER device fromMedtronic, Inc. of Minneapolis, Minn. Valve delivery system 2130includes a distal tip 2134.

In the delivery configuration of FIG. 21, second or distal capsule 2133is disposed over transcatheter valve prosthesis 1700 to compressivelyretain the transcatheter valve prosthesis in crimped engagement with theinner shaft (not shown) of the delivery system and first or proximalcapsule 2131 is disposed over straightened loops 1750 to retain them intheir delivery configuration. Valve delivery system 2130 is trackedthrough the vasculature until transcatheter valve prosthesis 1700 ispositioned within the native valve annulus as shown in FIG. 21. Deliveryof transcatheter valve prosthesis 1700 may be accomplished in accordancewith techniques known in the field of interventional cardiology and/orinterventional radiology. In an embodiment hereof, transcatheter valveprosthesis 1700 is configured for implantation in a target diseasednative aortic valve AV that extends between a patient's left ventricleLV and a patient's aorta A. The coronary arteries C_(A) are also shownon the sectional view of FIG. 21. Transcatheter valve prosthesis 1700 isconfigured for implantation via a percutaneous transfemoral approach andvalve delivery system 2130 is transluminally advanced in a retrogradeapproach through the vasculature to the treatment site. Moreparticularly, valve delivery system 2130 is tracked through the femoralartery, up the aorta and around the aortic arch in order to access thenative aortic valve AV. Transcatheter valve prosthesis 1700 may also bepositioned within the desired area of the heart via different deliverymethods known in the art for accessing heart valves.

After transcatheter valve prosthesis 1700 is positioned within thenative valve annulus as desired, second or distal capsule 2133 isslightly distally advanced as indicated by directional arrow 2260 inorder to expose a short segment of first or outflow end 216 of tubularstent 202 as shown on FIG. 22. Next, first or proximal capsule 2131 isproximally retracted as indicated by directional arrow 2364 in order todeploy self-expanding loops 1750 as shown on FIG. 23. In addition or asan alternative to retracting proximal capsule 2131, loops 1750 may bepushed or distally advanced out of proximal capsule 2131 via a push rod(not shown) or similar mechanism built into the delivery system. Whenloops 1750 are released from proximal capsule 2131, each loop 1750 ispermitted to self-expand and resume its deployed or expandedconfiguration as described above with respect to FIG. 20. At this stageof deployment, transcatheter valve prosthesis 1700 remains compressedwithin second or distal capsule 2133, except for a short segment at theoutflow end 216 of stent 202 which is partially deployed.

In FIG. 23, loops 1750 are shown deployed onto abutment surface 2337 ofthe native valve annulus. As such, loops 1750 are positioned in thecoronary cusps and are utilized as depth markers or reference points tolongitudinally center valve prosthesis 1700 by preventing the valveprosthesis from being positioned too deep or too shallow within the leftventricle LV. However, if loops 1750 deploy above abutment surface 2337of the native valve annulus, valve delivery system 2130 may bemanipulated in order to catch or contact deployed centering mechanism1720 onto abutment surface 2337 of the native valve annulus. Moreparticularly, valve delivery system 2130 may be distally advanced inorder to translate or move valve prosthesis 1700 and centering mechanism1720 until loops 1750 contact or abut against abutment surface 2337 ofthe native valve annulus as shown in FIG. 23.

Once loops 1750 are deployed and positioned as desired, valve prosthesis1700 is then deployed into the expanded configuration via distaladvancement of second or distal capsule 2133. Valve delivery catheter2130 is then removed as shown in FIG. 24 and transcatheter valveprosthesis 1700 including integral centering mechanism 1720 remainsdeployed within the native target heart valve. Deployment oftranscatheter valve prosthesis 1700 may thus be considered to occur viatwo consecutive stages with a first stage of deployment includingdeployment of centering mechanism 1720 and a second stage of deploymentincluding deployment of tubular stent 202 having a prosthetic valvecomponent therein.

While various embodiments according to the present invention have beendescribed above, it should be understood that they have been presentedby way of illustration and example only, and not limitation. It will beapparent to persons skilled in the relevant art that various changes inform and detail can be made therein without departing from the spiritand scope of the invention. Thus, the breadth and scope of the presentinvention should not be limited by any of the above-described exemplaryembodiments, but should be defined only in accordance with the appendedclaims and their equivalents. It will also be understood that eachfeature of each embodiment discussed herein, and of each reference citedherein, can be used in combination with the features of any otherembodiment. All patents and publications discussed herein areincorporated by reference herein in their entirety.

1. A transcatheter valve prosthesis comprising: a stent having acompressed configuration for delivery within a vasculature and anexpanded configuration for deployment within a native heart valve; aprosthetic valve component disposed within and secured to the stent; anda centering mechanism coupled to and encircling an outer surface of thestent, the centering mechanism having a compressed configuration fordelivery within a vasculature and an expanded configuration fordeployment within a native heart valve, wherein the centering mechanismincludes a centering ring that is self-expanding and has an expandeddiameter in the expanded configuration that is greater than an expandeddiameter of the stent in the expanded configuration and a plurality ofspokes that are self-expanding and radially extend between the stent andthe centering ring in the expanded configuration, and wherein thecentering mechanism in the expanded configuration has a flat profilethat extends transverse with respect to a longitudinal axis of thetranscatheter valve prosthesis.
 2. The transcatheter valve prosthesis ofclaim 1, wherein the spokes of the centering mechanism are formed from astrand of material that is woven between the stent and the centeringring.
 3. The transcatheter valve prosthesis of claim 1, wherein thecentering mechanism is configured to abut against a native valve annulusto longitudinally and circumferentially center the transcatheter valveprosthesis within the native valve annulus.
 4. The transcatheter valveprosthesis of claim 1, further comprising a flexible skirt attached toan outer surface of the centering mechanism.
 5. The transcatheter valveprosthesis of claim 4, wherein the skirt is formed from a low-porositywoven fabric or pericardial tissue. 6-7. (canceled)
 8. The transcathetervalve prosthesis of claim 1, wherein the plurality of spokes have athickness between 0.01 inches and 0.2 inches. 9-12. (canceled)
 13. Amethod of delivering a valve prosthesis configured for implantationwithin a native valve annulus, the method comprising the steps of:percutaneously introducing a valve delivery system into the vasculature,wherein the valve prosthesis is in a delivery configuration, the valveprosthesis including a stent, a prosthetic valve component disposedwithin and secured to the stent, and a centering mechanism coupled toand encircling an outer surface of the stent, the centering mechanismincluding a centering ring that is self-expanding and a plurality ofspokes that are self-expanding and radially extend between the stent andthe centering ring; tracking the valve delivery system through thevasculature until the valve prosthesis is positioned within the nativevalve annulus; and deploying at least an inflow end of the stent into anexpanded configuration, wherein the stent has an expanded diameter inthe expanded configuration; deploying the centering mechanism of thevalve prosthesis into an expanded configuration, wherein the centeringmechanism has an expanded diameter that is greater than the expandeddiameter of the stent in the expanded configuration and wherein thecentering mechanism in the expanded configuration has a flat profilethat extends transverse with respect to a longitudinal axis of the valveprosthesis; manipulating the position of the deployed centeringmechanism of the valve prosthesis such that the deployed centeringmechanism catches onto the native valve annulus, thereby longitudinallycentering the valve prosthesis within the native valve annulus; anddeploying an outflow end of the stent into the expanded configuration.14. The method of claim 13, wherein the spokes of the centeringmechanism are formed from a strand of material that is woven between thestent and the centering ring.
 15. The method of claim 13, wherein theplurality of spokes have a thickness between 0.05 mm and 0.5 mm. 16-20.(canceled)
 21. A transcatheter valve prosthesis comprising: a stenthaving a compressed configuration for delivery within a vasculature andan expanded configuration for deployment within a native heart valve; aprosthetic valve component disposed within and secured to the stent; anda centering mechanism coupled to and encircling an outer surface of thestent, the centering mechanism having a compressed configuration fordelivery within a vasculature and an expanded configuration fordeployment within a native heart valve, wherein the centering mechanismin the expanded configuration is configured to abut against a nativevalve annulus to longitudinally and circumferentially center thetranscatheter valve prosthesis within the native valve annulus.
 22. Thetranscatheter valve prosthesis of claim 21, wherein the centeringmechanism includes a centering ring that is self-expanding and has anexpanded diameter in the expanded configuration that is greater than anexpanded diameter of the stent in the expanded configuration and aplurality of spokes that are self-expanding and radially extend betweenthe stent and the centering ring when the centering mechanism is in theexpanded configuration, the plurality of spokes being formed from asingle strand of material that is woven between the stent and thecentering ring.
 23. The transcatheter valve prosthesis of claim 22,wherein the single strand of material is woven between cells formedwithin the stent and loops around the centering ring.
 24. Thetranscatheter valve prosthesis of claim 22, wherein the spokes aresubstantially straight when the centering mechanism is in the expandedconfiguration.
 25. The transcatheter valve prosthesis of claim 22,wherein the centering mechanism in the expanded configuration has a flatprofile that extends transverse with respect to a longitudinal axis ofthe transcatheter valve prosthesis.
 26. The transcatheter valveprosthesis of claim 22, wherein the centering mechanism includes exactlyeight spokes that are circumferentially spaced apart with respect to thestent.
 27. The transcatheter valve prosthesis of claim 22, wherein theplurality of spokes have a thickness between 0.05 mm and 0.5 mm.
 28. Thetranscatheter valve prosthesis of claim 21, further comprising aflexible skirt attached to an outer surface of the centering mechanism.29. The transcatheter valve prosthesis of claim 28, wherein the skirt isformed from a low-porosity woven fabric or pericardial tissue.
 30. Thetranscatheter valve prosthesis of claim 1, wherein the centeringmechanism includes exactly eight spokes that are circumferentiallyspaced apart with respect to the stent.
 31. The transcatheter valveprosthesis of claim 1, wherein each spoke of the plurality of spokes isa strand of material having a first end attached to the centering ringand a second end attached to the stent.